1. Field of the Invention
The present invention relates to an image forming apparatus that can detect a malfunction of an operation unit, and that can control execution of a print job.
2. Description of the Related Art
A touch panel has been used for an image forming apparatus according to related art. Due to recent popularization of a smart phone and a tablet computer, operability of a touch panel is improved. For example, text input by flick input and an operation by multi-touch are possible. A main cause of the improvement of the operability may be popularization of an operating system (OS) which is referred to as “Android (registered trademark).” An attempt is made to apply this OS to an operations panel of an image forming apparatus.
In general, robustness and stability of a new OS is improved as upgrading of the new OS is continued. When a new OS is implemented for a touch panel, it is possible that the OS is abnormally terminated (the OS abends) at an unexpected timing during operation.
When an OS is abnormally terminated, a user's operation may not be accepted. Thus, cancellation of a print job may be desirable. A technique is known which is for cancelling a print job (cf. Patent Document 1 (Japanese Unexamined Patent Publication No. 2008-207539), for example). Patent Document 1 discloses an image forming apparatus such that it starts measurement of time after a print job is cancelled by a user by pressing a print stop/restart key, and it restarts the print job at a time at which an elapsed time exceeds the set time, provided that the print stop/restart key is not pressed again.
Unfortunately, according to the image forming apparatus which is disclosed in Patent Document 1, a print job may not be cancelled unless a user performs an operation to cancel the print job. Namely, when the OS is abnormally terminated at the unexpected time, the OS is in a state where the OS is not operable, until the OS is restarted. For example, it is possible that the OS is abnormally terminated immediately after the user erroneously made a print request. When the OS is abnormally terminated, the user may not cancel or stop the printing which is accepted by the operations panel, until the OS is restarted. A problem is that a sheet of paper which is not desired by the user may be output.
In view of the above problem, an objective of the present invention is to provide an image forming apparatus that can prevent outputting of a document during a state where a user may not cancel printing by operating an operations panel.